Pneumatic control systems are widely used for holding a variable of a medium approximately to a set point. Many circumstances cause deviation from the set point, however; and pneumatic control systems overshoot, undershoot, and fluctuate as the load and other conditions vary.
Fluctuation in the controlled medium can waste energy and cause many problems so that it would be much better for pneumatic control systems to bring the medium variable quickly to a control point and accurately hold it there. My invention helps achieve this with simple and effective equipment that can be installed easily in both existing and future pneumatic control systems. It can be adjusted to accommodate many different circumstances, it can narrow the required throttling range for the system, and it greatly improves on efficient and accurate operation.